Rotary pump



P 1932- P. c. PETERSEN 1,877,688

ROTARY PUMP Filed April 16, 1931 f INVENTOR .P. C. Petersen,

Patented Sept. 13, 1932 UNITED STATES PATENT orricr.

PETER G. PETERSEN, OF CEDAR FALLS, IOWA, ASSIGNOR TO VIKING PUMP COMPANY, 01 CEDAR FALLS, IOWA ROTARY PUMP Application filed April 16,

My invention relates to improvements in rotary pumps, and an ob ect of my improvements is to provide means in such a pump which will upon the inception of back preschamber 19 eccentrically,

sure in its discharge port caused by the shutting off of a valve'in adeliver hose therefrom, cause relative recession 0 a piston element to permit the pistons to race while relieving the back pressure between them.

Another object of my improvements is to provide means for reactive resilient controlling of said receding element to return it to its former position for service.

Another object of my improvements is to include with said resilient means packing means for preventing leakage therebeyond.

Another object of my improvements is to provide outlet passages respectively from both the suction and the discharge chambers to the rear part of the pump chamber back of the recessive piston element, with means for removably plugging either of these passages, whereby the liquid in the cavity to the rear of the said piston element is evacuated when this element is shifted by back pressure thereinto, and whereby either of the outlet passages may be used for this purpose, when the engine is reversed.

I have accomplished these objects by the means which are hereinafter described and claimed, and which are illustrated in the accompanying drawing, in which Fig. 1 is a vertical longitudinal axial section of my improved rotary pump, with a portion of the driving shaft broken away, and Fig. 2 is a front elevation of the pump, with the faceplate or cylinder cover removed and with parts shown in cross section.

In the rotary pump shown, 1 is the base of the frame which includes the forwardly projecting cylinder 2 having an open front end with a removable head 3 secured by screws 5. The head 3 has a bossed part 4 in which is fixed ashaft 6 extending into the cylinder its inner part being surrounded by a bushing sleeve 7, and an idler piston gear 12 being rotatable on said bushing and having tee h 13 with concaved side walls.

The numeral 20 denotes a rotary driving 1931. Serial in). 530,564.

shaft mounted in the pump body and having w1t-hin the pump chamber 19 a rotor piston or gear 15 having on its front face forwardly projecting crown teeth 16 having convex side walls, these teeth being thus shaped to fit and mesh with the concave teeth 13 of the idler 12 at times. The cylinder head has an integral inwardly projecting crescental member 14 which is interposed between the said idler 12 and rotor 15 to fill the gap therebetween and p event passage therebetween of liquid being pumped. The pump construction thus far described is well known in this art, and our improvements hereinafter described are especially related thereto, but may be used in any modified forms .to cooperate with the like elements or varied elements in other rotary pumps.

The cylinder 2 has at ninety degrees apart circumferentially an inlet or suction port 17 and a discharge port 9, respectively directly in communication with intermediate chambers 18 and 8 which open into said central or pumping chamber 19. The pumping chamber 19 is long enough from front to rear to leave a cavity back of the rotor 15, when the rotor is in its forward and fully meshed position with the idler 12 as shown in Fig. 1. A portion of the liquid being pumped tends to gradually accumulate in this rear cavity, which impedes the recession of the rotor 15 at times, and I have provided like discharge passages 10 in the cylinder wall, one or the other of which is plugged as at 11, so that the contents of the cavity mav be delivered into the proper communicating intermediate chamber 8 or 18, and to the suction port 9 or 17, as the case may be, when the pump is reversed.

A sleeve 21 is mounted and splined non-rotatably on the forward part of the shaft, and the rotor 15 is iixed on this longitudinally slidable sleeve to move therewith. The rear frame part has a hollow 23 traversed coaxially by the shaft 20. A shouldered bearing bushing 22 lines the forward part of this hollow to fit the sleeve 21, and its shoulder prcvents its shifting forwardly into the chamber 19.

The rear part of the frame hollow 23 is closed by a shouldered closure 30 centrally apertured to receive a shouldered bushing 29 traversed by the shaft 20. The closeure 30 may be secured by screws 31. Within the hollow 23a coiled spring 26 surrounds said shaft and is seated between the hollow members 24 and 25, the latter spaced concentrically from the shaft to receive said spring. The facing ends of the members are open, but their outer ends are closed by hub parts, the hub of the member 24 engaging the abutting end of the sleeve 21, and the hub of the member 25 engaging the inner shouldered end of the bushing 29. The numeral 28 denotes a pair of rubber packingwashers within the member 25 engaging its hub, and the numeral 27 denotes another washer seated in an annular groove 20' in the shaft 20 and contacting the forward one of the washers 28, this washer being engaged on its opposite face by the abutting end of the spring 26, the forward end of the spring engaging the hub of the. member 24. The spring 26 presses upon the washers 27 and 28 and these upon the hub of the member 25, and the latter upon the bushing 29, thus sealing the hearing at the rear end of the frame against leakage. The spring being always under tension, yieldingly forces the sleeve and rotor 15 toits forward meshed position as shown in ordinary use.

When a hose is connected to the discharge part of the pump to be in direct communication with its discharge port 9, the hose having on its outer end the usual valve-controlled nozzle, as for use in gasoline service stations, it often occurs that the operator has to close the nozzle valve when it is inconvenient for him to shut off the motor for the pump. In this case, a back pressure builds up within the pump, and also in'the hose, tending to rupture the hose. With the above construction of my improved pump, this back pressure in the chamber 19 in front of the rotor 15 is enough to shift it back to compress the spring 26, the oil if any in the rear part of the chamber back of the rotor escaping by way of either passage 10 which is in use. This affords room between the rotors for the liquid to pass between them as indicated by J the dotted lines in Fig. 1, so that the still meshed rotors run idly, the back pressure being relieved.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is:

In a rotary pump, a cylinder having ports, and having shaft bearing leading centrally into the cylinder, low of different diameters, a driving shaft seated in said hollow and in its fitting part and to extend into the cylinder, the outer end of the wider part of said hollow opening outwardly, an apertured closure for the outer end of said hollow containing a shoulsaid bearing having a holdered bushing fitting said shaft, and stop ed by its shoulder against the closure, comes ed piston gears in said cylinder of lesser len th than the cylinder, one gear being slida 1y mounted limitedly upon said shaft to move longitudinally in the cylinder without becoming unmeshed and while under back pressure of liquid from the discharge port, resilient means in said hollow bearing against said gear to return it into full mesh, and also sealing devices in the hollow engaged by the resilient means to prevent leakage at said bushing.

In testimony whereof I afiix my signature.

PETER G. PETERSEN. 

